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Thread: Wrong ECM OS?

  1. #1
    Tuner in Training
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    Wrong ECM OS?

    Have a 2009 Pontiac G8 GT Automatic. Built motor, Procharger (we didn't build it). Doing some weird things on dyno. Began looking at all your previous posts and read about IFR limitation of 63.5 on the E38 computers. This motor has 85# injectors which is what is loaded into the Injector Flow Rate vs Pressure table. Thought that might be part of the problem but then noticed a post about an 2009.5 ECM that doubled that limit to 127. Looked at the tune in Editor and that is the limit stated for this table. But this car was built in October 08. Began thinking we might have the later ECM so I looked up the OS # 12633016 from the tune file. This is listed for a 2009 Manual car, not an automatic. Yet it's running here and tranny has been tuned by Circle D. Much head scratching ensued.

    Any thoughts?
    Cheers,
    Rick Robinson
    American High Performance
    Lorton, VA 22079
    703-339-7412
    http://www.americanhighperformance.com


  2. #2
    what problem are you having?

    You can check the VIN/OS at:

    http://tis2web.service.gm.com/tis2web
    I count sheep in hex...

  3. #3
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    Thanks for replying, Chris.

    Started with the car's previous tune (not ours), returned all ECM parameters to stock except MAF curve, injector profile and spark tables and then started dialing back in. Smoothed out MAF curve on street and then took to dyno. AFR curve was pig rich which wasn't a big concern but it has this wierd lean bump at about 4200 RPM. Jumps from off scale to almost 12 for about 500 rpm then back rich. Nothing else indicated on any of the logged data. Concerned that if we start bringing the rest of the curve back up, this part goes dangerously lean. I'll post the curve tomorrow. Don't have it here with me tonight.

    Only thing I note in the physical setup is that they left the 1 bar MAP. Pegs at 120 Kpa just about the same time the AFR bumps. Might think that was related but then why does it recover to <10?
    Cheers,
    Rick Robinson
    American High Performance
    Lorton, VA 22079
    703-339-7412
    http://www.americanhighperformance.com


  4. #4
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    By the way, thanks for the link. Confirmed we have the correct calibration. Other website (tunfiledepot) apparently had bogus data.
    Cheers,
    Rick Robinson
    American High Performance
    Lorton, VA 22079
    703-339-7412
    http://www.americanhighperformance.com


  5. #5
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    Attached are the dyno graph showing the AFR bump and the Scanner file. Just to let you know, it wasn't a one time fluke. This was the second of two pulls and it repeated on both.
    Cheers,
    Rick Robinson
    American High Performance
    Lorton, VA 22079
    703-339-7412
    http://www.americanhighperformance.com


  6. #6
    Senior Tuner edcmat-l1's Avatar
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    There's nothing in the data log to suggest that A/F reading is real. Must be something screwy with the dyno WB, or the exhaust sampling or something. What the WB showing is not what's actually happening.

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  7. #7
    make sure its not setting P0106 and/or P0108 (set them to 2 No MIL). Pegging at 10:1 then swinging to 12:1, then back to pegged 10:1 is a big change and you'd expect to see some bigger dips on the charts as posted above.

    As a quick test i would add some more fuel into the PE table around 4000-4500 rpm and see if it changes things.

    Chris...
    I count sheep in hex...

  8. #8
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    Quote Originally Posted by edcmat-l1 View Post
    Must be something screwy with the dyno WB, or the exhaust sampling or something.
    Thought it might be a screwy WB reading as well but it did it consistently at the same spot on two pulls. A bad WB would most likely be erratic.

    Will try to 'gently' nudge it as you suggest Chris and see what happens.
    Cheers,
    Rick Robinson
    American High Performance
    Lorton, VA 22079
    703-339-7412
    http://www.americanhighperformance.com


  9. #9
    It could be going rich enough to blow spark out causing a puff of unburnt air to go into the exhaust causing the wideband to read lean.

    Does it buck on the dyno?

  10. #10
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    Quote Originally Posted by meatbag View Post
    Does it buck on the dyno?
    Nope. Nice smooth pull all the way. We have a Mustang that needs a baseline. We're going to put it on there first and see what the readings look like to verify the dyno setup.

    One of the other problems this car has that motivated customer to want to retune it surfaced when I was tuning transmission (with help of Circle D). Every thing looked good except......on a hard throttle downshift the engine would just fall on its face for a couple of seconds, then recover and take off. As you can see from attached scan file (about 2/3 way through scan), I hit it to WOT, trans drops from 6th all the way down to 2nd gear, RPM starts to climb, then spark falls away and throttle slaps closed to 26%. Stumbles along for a second or two, then recovers and on its way. Haven't come up with any reason for this either. The two don't seem to be related as they are not in the same RPM or MAF Hz range as the dyno problem.

    Car's possessed. Maybe it's because it's an Aussie car. Everything is upside down.
    Cheers,
    Rick Robinson
    American High Performance
    Lorton, VA 22079
    703-339-7412
    http://www.americanhighperformance.com


  11. #11
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    Quote Originally Posted by rick@ahp View Post
    Maybe it's because it's an Aussie car.
    Actually Chris, your Holden boys build a pretty nice car. For a four door sedan, this one's pretty sweet.
    Cheers,
    Rick Robinson
    American High Performance
    Lorton, VA 22079
    703-339-7412
    http://www.americanhighperformance.com